There is a significant interest in preparing polymers from materials derived from biomass. The diol 1,4:3,6-dianhydro-D-sorbitol, hereinafter referred to as isosorbide, is readily made from renewable resources, such as from sugars and starches. According to the following reaction scheme, isosorbide can be made from biomass derived starch through hydrolysis, hydrogenation, and dehydration reactions.

Isosorbide has been used as a monomer in the subsequent formation of copolycarbonate polymers as described in U.S. Pat. No. 7,138,479. This patent notes that copolycarbonates of isosorbide with BPA and homopolycarbonate of isosorbide made by the melt route using BMSC or DPC as the carbonate source may discolor when exposed to high temperatures greater than 250° C. Residual catalyst in the polycarbonate is indicated as a potential contributor to the discoloration. Isosorbide is also listed as a possible aliphatic diacid comonomer for inclusion in polycarbonates in U.S. Pat. Nos. 7,132,498 and 7,041,775.